For 45 years, an international treaty has barred countries from laying claim to the moon and other celestial bodies — but some policy analysts say private ventures might be able to stake their claims, and they want Congress to create a legal framework that takes advantage of the "loophole."

The concept was unveiled last week by Rand Simberg, an adjunct scholar at the Washington-based Competitive Enterprise Institute, and it aims to take advantage of the same market incentives that drove the settlement of the American frontier. The way Simberg sees it, the lack of property rights in space "partially explains why we have not developed the next and, in a sense, last frontier — space."

The inability to claim sovereignty over other worlds goes back to the 1967 Outer Space Treaty. A hundred countries, including the United States and all the other spacefaring nations, are parties to that treaty.

Yet another treaty, drawn up in 1979, bars private ownership of extraterrestrial property in the solar system — but that pact, known as the Moon Treaty, has not been ratified by any of the world's spacefaring nations. The differences between the two treaties suggest that it's possible to have private ownership without national sovereignty, and that's the loophole that Simberg wants to take advantage of.

Multibillion-dollar incentive?Backers of the proposed legislation, known as the Space Settlement Prize Act, say it could create, "at no cost to taxpayers, a multibillion-dollar incentive for private companies to finance and build permanent settlements on the moon and/or Mars."

The proposal would set up a process for the U.S. government to recognize ownership of extraterrestrial territory if a private venture establishes a permanently inhabited settlement on another world. For example, the first venture to establish a moonbase could lay claim to up to 600,000 square miles of the lunar surface. Having the first Mars base would entitle the operators to up to 3.6 million square miles of the Red Planet. Putting a permanent base on an asteroid could be rewarded by with up to 1 million square miles of surface area, depending on how big the asteroid was.

The owners would have to guarantee that anyone could buy a ticket to travel to the territory. Each succeeding settlement group would be allotted 15 percent less land than their predecessor. And if two potential claimants couldn't resolve a land dispute, U.S. courts could step in.

But doesn't that sound like sovereignty?

"In some sense, it gives the imprimatur of the U.S. government," Simberg said. "But it doesn't make it a sovereignty question. It's a recognition, not an appropriation." He said the first commercial moon colonies could well be headquartered in different countries. In that case, the United States would be recognizing the property rights of non-U.S. ventures on another world.

What would the U.S. do?Simberg emphasized that the federal government wouldn't be obligated to take any action to defend extraterrestrial property owners. "How the U.S. government would respond to future claims and conflicts of claims on the moon would be entirely a political decision," he said.

Some legal experts say the loophole doesn't really exist. They point to a section of the Outer Space Treaty that holds national governments responsible for the space settlement activities of their citizens, and say that would preclude any effort to uphold property claims.

"Even if the United States withdrew from the treaty in order to implement such land grants, what would stop the Chinese from adopting domestic legislation that went further?" Berin Szoka and James Dunstan asked in an essay published by Wired. "What if the first time a Chinese probe lands on the moon, the moon could be claimed by the 'Great Wall Company,' owned by the People’s Liberation Army? The United States would then be left to argue that our law should be followed, but the Chinese law shouldn’t. That’s precisely the kind of territorial jockeying the Outer Space Treaty was intended to prevent."

Simberg said a lunar land grab would almost certainly not play out that way. If Chinese leaders really wanted to take over the moon — a scenario that billionaire Robert Bigelow laid out last year — all they'd have to do is withdraw from the Outer Space Treaty and do what they will. "They wouldn't try to play this legislative game," Simberg said.

Why go to the trouble?The bigger question is, why would anyone go to the trouble of claiming the moon, or Mars, or an asteroid? Right now, there's nothing out there that's worth the hundreds of billions of dollars it would take for a commercial venture to set up its own space program and establish a beachhead beyond Earth. But Simberg and his colleagues say that situation could change if the cost of spaceflight goes down and the perceived value of extraterrestrial resources (helium-3?rare earth elements?) goes up.

Simberg acknowledged that he's thinking about the long-term future of beyond-Earth settlement rather than short-term campaign issues. "Nothing like this is going to pass this year," he said. What he'd love to see is a new international process that takes the place of the Outer Space Treaty and provides a jump-start for private-sector space colonies.

"The treaty's outdated," he said. "It just doesn't work. I don't think anyone back then could conceive of a private launch system based on the Isle of Man, launching somebody into orbit who would then be transferred to L1 [an Earth-moon transfer point] on a tug that was run out of Dubai, and then to a lander operated by somebody in Australia."

Does all this sound like science fiction, or future science fact? Feel free to register your vote in the poll above, or share your opinion as a comment below.